2026/05/31 by Anonymous, Piotr Habdas, Rachel E. Courtland +1
Chemistry · Materials Science · Physics and Astronomy · #Advanced Physical and Chemical Molecular Interactions #Colloid #Colloidal particle #Electrostatics and Colloid Interactions #Glass transition #Material Dynamics and Properties #Perturbation (astronomy) #Phase transition #Rheology #cond-mat.soft
paper · pdf · doi:10.1103/pq16-v16h
openalex publication_date 2026/07/24 · openalex created_date 2026/07/25 · openalex updated_date 2026/07/25 · arxiv created 2026/08/05 · arxiv updated 2026/08/06
Isolated microscopic magnetic particles are used to induce local perturbations in dense colloidal suspensions by rotating an external magnet. Confocal microscopy enables tracking of both the magnetic probe particle and adjacent colloidal particles. A probe particle moves with a circular trajectory. Knowing the external force and measuring the amplitude and phase of the probe motion allows us to infer the storage and loss moduli of colloidal suspensions at various volume fractions. These measurements are in qualitative agreement with previous results from conventional rheology. To further analyze the system's response, the oscillatory amplitude of colloidal particles is evaluated as a function of distance from the probe, revealing a 1/r decay in amplitude, consistent with a homogeneous viscoelastic material. These observations confirm that continuum descriptions of the colloidal samples are effective down to length scales comparable to the particle diameter.